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Immunoglobulin G (IgG) Subclass 1, Mass Concentration (Serum/Plasma)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of Immunoglobulin G (IgG) subclass 1, a type of antibody in your blood. IgG1 helps protect your body from infections and is important for long-term immunity.

Quick summary

["IgG1 antibodies play a key role in fighting infections and maintaining immunity over time."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
100789-7
Short code
R nigricans IgG4-mCnc
Synonyms
R nigricans IgG4-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Does This Test Measure?

IgG1 is one of the four subclasses of Immunoglobulin G (IgG), a primary antibody in your immune system. This test specifically looks at the concentration of IgG1 in your blood, which can vary depending on your immune response, health status, or certain medical conditions.

Why Might You Need This Test?

Doctors may order this test to evaluate immune function, diagnose or monitor conditions affecting antibody levels, or assess responses to treatments like vaccines or therapies targeting antibodies.

Common Reasons for Testing

Common reasons include evaluating immune deficiencies, monitoring autoimmune diseases, checking for infections, or assessing how well a patient responds to antibody-based treatments.

Sample Collection and Preparation

Blood is typically drawn from a vein in your arm. The sample is collected in a tube and sent to a lab for processing. This test is usually done on serum or plasma, which are parts of your blood separated after clotting or centrifugation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG1 Level

Frequently asked questions

How might low or high IgG1 levels affect my health?
Low levels of IgG1 may indicate an immune deficiency, where your body struggles to produce enough antibodies to fight infections. High levels could be seen in certain autoimmune conditions or chronic infections, but interpretation depends on clinical context and other test results.
What does it mean if my IgG1 level is outside of normal ranges?
Results outside normal ranges should be discussed with your healthcare provider. They will consider your overall health, symptoms, and other test results to determine if further action is needed, such as additional testing or treatment adjustments.
Can diet or lifestyle affect IgG1 levels?
Diet and lifestyle factors like nutrition, stress, and overall health can influence immune function, but they do not directly affect IgG1 levels. Your provider may recommend lifestyle changes if they believe they support better immune health.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy